This invention relates to an anchor post, defined by a projection which extends from a wheel bearing housing, for a drum-in-hat park brake to provide resistance to rotative torque developed on engagement of friction pads with a drum during a brake application.
In most vehicles with four wheel disc brakes, the disc brake associated with the front wheel is attached to a steering knuckle assembly. The steering knuckle assembly is usually constructed as a one-piece forged or cast unit which includes a wheel bearing carrier, torque arms for supporting a disc brake caliper and points of attachment for suspension joints. In order to reduce the weight of a steering knuckle assembly is has been suggested that certain components could be stamped from steel plates. This type of steering knuckle performs in a satisfactory manner and is disclosed in the prior art of which U.S. Pat. Nos. 3,940,159 and 4,518,159 may be considered to be illustrative.
The disc brake assembly for the rear wheels for a vehicles is usually achieved by the attachment of an anchor plate to the housing of the rear axle. In this type brake the anchor plate is made from a cast material and may include a support abutment for first and second brake shoes associated with a drum-in-hat emergency or park brake as disclosed in U.S. Pat. Nos. 5,180,037 and 5,865,275.
In recent years the length of some vehicles and in particular trucks, has increased to an extent that the overall ease in maneuverability such as turning a sharp corner has been reduced. In order to retain a desired control over the vehicle and yet provide an economy associated with a larger vehicle, it has been suggested that the rear wheels have the capability to be steered in coordination with the front wheels, i.e. four wheel steering. Unfortunately, the manufacture and assembly of the front wheel components and rear wheel component for a vehicle do not occur as a simultaneous function and as a result damage to the support abutment may occur in the shipping from one location to another location.
A primary object of the present invention is to replace a support abutment for a drum-in-hat park brake provided on an anchor plate for a disc brake assembly with a projection which extends from a wheel bearing housing fixed to a suspension/steering knuckle for a vehicle.
The present invention relates to a wheel bearing housing and a backing plate for a drum-in-hat brake assembly. A first brake shoe is retained on the backing plate by first pin and a second brake shoe is retained on the backing plate by a second pin. The first and second pins permit the first and second brake shoes to be moved in a radial plane and have limited rotational capability about an axis of an opening in the backing plate. The first and second brake shoes each have a first engagement end which is aligned on the backing plate by an anchor post extending from the wheel bearing housing and a second engagement end which is selectively spaced apart by an adjuster mechanism. A spring arrangement urges the first and second brake shoes toward the anchor post and into engagement with the adjuster mechanism. An actuator assembly is connected to the first engagement end of the first and second brake shoes and upon receiving an input force moves first and second friction pads associated with the first and second brake shoes into radial engagement with a drum. The radial engagement causes the first and second brake pads to rotate and bring one of the first engagement ends into contact with the anchor post. The anchor post provides resistance to the rotation of the first and second brake shoes during a corresponding brake application. The anchor post is characterized by a projection which extends from a wheel bearing housing fixed to the knuckle for a suspension system and steering linkage to provide direct link between a fixed support on the vehicle and the first and second shoes to resist rotative torque developed through the engagement of the friction pads with the drum during a brake application.
An advantage of the instant drum-in-hat park brake resides in the use of a projection that extends from the housing of a wheel bearing as a support abutment for first and second brake shoes to resist braking torque to take advantage of the high strength provided by the material composition of the bearing housing.
A further advantage of the instant drum-in-hat park brake is in the ease whereby a wheel bearing housing, first and second brake shoes, an adjuster and actuator secured to a backing plate of a drum-in-hat park brake are attached to a knuckle associated with the suspension system and steering linkage for a vehicle to allow an axle to be directly installed in a vehicle.